The update for Dragon Quest Builders 2 is a maintenance patch primarily focused on social features and minor stability, rather than new gameplay content. For the US Switch version, this update addresses a critical bug that prevented user-uploaded images from appearing on the in-game Bulletin Board. Update Overview Release Date: March 19, 2020 (US Switch).
If you are managing the game via NSP files on a modded console: Dragon Quest Builders 2 -NSP--US--Update 1.7.3-...